Diaphragm.



c stances of cardboard .moon nusen, or omsymmnsora.

nermen.

Speciflcation of Letters Patent.

Application filed April 8, 1915.' Serial Ilo. 19,919.

To all whom z't may concem:

Be it known that I, JAcoB Essen, a subject of the. Kin of German residing at Minneapolis, in t e county of' ennepn and State of Minnesota, have invented certain new and useful Improvements in' Diaphragms, of which the following is a specification. p

My invention relates to diaphragms for talkin machines, and has for its object to provi e a novel and useful diaphragm which shall be possessed of peculiarly eflicient and desirable characteristcs in the reproduction of sounds from talking machines.

The diaphragms commonly employed are formed of mica or celluloid and in some inin which deposits or layers of metallic fillers have been formed or impregnated after the cardboard has been fabricated. A rincipal defect of all such diaphragms has been that the sound reproduction has been harsh and metallic, and certain sounds, particularly the high or treble notes of the human voice, have been repro duced in a blasjted and unpleasant manner. I have discovered that a daphragm made in accordance with my invention herem de scribed obviates this defect in the reproduction while very greatly increasing the sound producing qualities o the talking machine.

The invention consists prmarly m the formation of a diaphragm from the well known commercial article of manufacture known as trunk fiberby means of the reduction of the thickness of said trunk fiber through scraping, grinding, or polishing.

The so-called trunk fiber .is a well known article of. commerce formed of wood fiber and silk or other textile fabrics united by a special binder under ve great pressure, whereby there is rodu a erfectly uniform substanca o great har ess, density and toughness which is waterproof, ressts the action of moisture in'the atmosphere, is non-fracturable, flexible, elastic, and as I have discovered is po in a hgh degree of the capacity for vibraton. The unform character of this substance makes it to reduce the same b grinding, pol g or scrapngwthout a ecting the character of the remanng material or of the surface of the reduced diaphragm, diflering in this partcularwholly from common wood fiber board, whch requires a special glazing of the surface put in during manufacture and cannot cut down through this surface without mterfering with the character of the materiali In the drawings illustratingthe applicaton of my mvention in one form, Fgure 1 s a section of a piece of trunk fiber showing the thickness of the same. Fig. 2 is a plan view of a diaphragm made in accordance with my method therefrom. Fig. 3 is a section throu h said diap hragm showing its slghtly doub -concaved form.

The trunk fiber-is formed in sheets of a normal thickness of about one-eighth of an mch, which, as above pointed' out, is absolutely uniform in character throughout the thckness thereof. This trunk fiber can be sera ed, ground, or polished to any desired thc ess, and when reduced to` a very thin sheet, even much thinner than is desirable for n diaphragm, it still ossesses all the qualtes of toughness, dura ility, hardness, and capacity for vibration -of the original material.

In producing my diaphragm, I cut from the trunk fiber 10 a circular disk 11' of the %reper diameter for use as a diaphragm.

hereafter, by scrapingrinding, or polishing, I reduce the thic ess of this disk, as indicated in Fig. 3, rendering the same slightly concave on both sides. Various thicknesses may be employed with different results as to Volume and qualit of sound. I have found that a thickness o about onesixty-fourth of an inch produces the Volume of sound of the most p easing quality. V

The advantages of my invention are obvious. The diaphragms produced thereby are cheap to construct, extremely strong and Patented Sept. 26, 1916.

atest ossible durable, do not deteriorate from use or under changing weather conditions, are highly vibratory, and have the qualiy of receiving and transmitting vibrations n such manner as not to change the timbre of ?he resultin sound, thereby reproducing Instrumenta and vocal musical numbers and human speech in a thoroughly natural and pleasing manner.

I claim: 1 A sound-reproducing diaphragm formed of truk fiber reduced to a suitable thckness. In testimon whereof I aflix my signature in presence o two witnesses.

JACOB RESCH. witnesses:

F. A. WHITELEY, HARnmT A. CREW. 

